Calcium–Lead Hydroxyapatites: Thermal and Structural Properties and the Oxidation of Methane

In Situ XRD and In Situ IR Spectroscopic Analyses of Structural Change of Goethite in Methane Oxidation

“…The reaction was started at as low temperature as 573 K on goethite (12). Under the present conditions, carbon dioxide and water exclusively were produced.…”

Interdependence of Anion and Cation Exchanges in Calcium Hydroxyapatite: Pb2+ and Cl−

“…Although the mechanism by which such enhancement occurs is not completely understood, the exposure of the catalyst to TCM leads to significant concentrations of chlorine, in whatever form, in both the surface and the bulk, as well as to the conversion of CaHAp to chlorapatite. Furthermore, the substitution of calcium by lead substantially and beneficially alters the catalytic properties of the apatite in oxidation processes (12). Although in the catalytic investigations the substitutions of Ca 2ϩ and OH Ϫ by Pb 2ϩ and Cl Ϫ , respectively, occur through two dissimilar processes, the former from solution, the latter from the gas phase, studies of these exchanges from liquid media provide useful information.…”

Preferential occupancy of metal ions in the hydroxyapatite solid solutions synthesized by hydrothermal method

“…Sugiyama et al 8 prepared Pb-Ca HAp solid solutions by the aqueous reaction from NaHPO 4 ·12H 2 O, Ca(CH 3 COO) 2 ·H 2 O, and Pb(CH 3 COO) 2 ·3H 2 O and after calcination at 773 K for 3 h they investigated their activities in the conversion of methane with nitrous oxide and oxygen as oxidants. They also investigated the influence of Pb-Ca HAp on the thermal property and structure, but they did not describe the occupancy site of Pb in the apatite structure.…”